Starting and accelerating device for motors.



w. s. SMlTH.

STARTING AND ACCELERATING DEVICE FOR MOTORS.

APPLICATION men APR. 19, 1912.

1, 16?;946. I Patented Jan. 11, 1916.

34 6 RESISTANCE 26 0 RESISTANCE UNITED sTATE'srATEN'r OFFICE.

WILLIAM s. SMITH, or CAMBRIDGE, MASSACHUSETTS" STARTING iAND-ACCELERATING DEVICE FOR MOT OBS.

Specification of Letters Patent.

Patented Jan. 11, 1916.

Application filed April 19, 1912. Serial No. 691,971.

. To all whom it may concern:

, starting resistances interposed in the armature or motor circuit areout out in successive steps by electro-magnets.

My device is particularlyappllcable to motors used for operatingelevators, but it is obvious that it can be applied to any electricmotor.

My object has been to provide a device by means of which the severalsections of resistance interposed in the armature circuit areautomatically successively cut out as the speed of the armatureincreases, by means of magnets energized from a shunt-circuit ofcomparatively high resistance having a practically constant flow ofcurrent, the adjustment and operation of said magnets being such that acurrent greater than a predetermined value cannot pass through thearmature-circuit under normal conditions, during the interval ofstarting the motor. I have illustrated and described my device as havingthree such resistances interposed in the armature circuit and withproper connections for the successive cutting out of these severalresistances. It is obvious, however, that my invention is adapted foruse in connection with either a larger or smallernumber of suchresistances and is capable ofsuch adjustment that the strength of theseveral resistances may all be alike or difierout as occasion requiresand the rate of cutting out such resistances can be adjusted atpleasure.

The accompanying drawing is a diagrammatic view embodying the featuresof my invention. a

1 and 2 represent the positive and negative lines of a main supply orprimary circuit.

3 is a switch for closing the circuit to the motor and its connectionsand the shuntcircuit hereinafter referred to, and may, if desired. havecontacts so that the direction of rotation of the motor may be reversedat the will of the operator. It may also have other contacts for closingother and auxiliary circuits necessary for the use to which the motor isput. I have purposely shown the most simple form of switch with separatecontacts, in order that the features embodied in my invention may bemore readily understood.

4. is an electric motor shown as a shuntmotor with shunt-field 4 ,.butit will 'be un-.

derstood that my invention is applicable as Well to a motor having aseries winding or a compound winding.

5 and 6 are the positive and negative lines 7 of a shunt-circuit ofcomparatively high re sistance and connected with the main circult bymeans of switch .3. It will be observed that this circuit has a currentof practically constant value.'

7 and 8 are the positlve andnegative lines of a main or armature-circuitwhich is connected with the main supply circuit by means of switch 3.- bI 7 and 9 are the positive and of a shunt-circuit of an electricmotorpass ing through shunt-field 4 and are also connected with the main lineby switch 3.

10, 10 10 are resistances interposed in the main or' armature-circuit.

11, 11 11 are magnet-coils interposed in the shunt-circuit 56 andrespectively wound on magnet-cores 17, 17 17-. These negative lines.

magnet-coils, 11, 11 11*, are illustrated as" i being connected inseries, but it is obvious -that the same result herein described andclaimed may be accomplished by other wellknown methods, such forinstance as'connecting said magnet-coils in parallel or bv utilizing asingle magnet having one coil withseveral magnet-cores.

12, 12, 12? are contacts respectively "wronnected by wires 33, 33*, 3333 with line 30 of the armature-circuit.

13, 13, 13 are arms respectively movably mounted on posts 14, 14 14- andare prefer-' ably constructed of magnetic material so as to be attractedby magnet-cores 17 17 17 when the same are properly energized. I do Inot, however, limit myself to the precise construction shown. as itwould be perfectly feasible to have the arms constructed of nonmagneticor insulating material with a plate or other attachment of magneticmaterial affixed thereto in position to be operated on by said magnets.There is, however. an advantage in the construction which I haveillustrated which consists in having the magnet and post sup-.magnet-cores 17, 17, 17

porting the movable arm and the arm itself constructed of magneticmaterial for the reason that it facilitates the operation of saidmovable arms when said magnets are energized by setting up a magneticflux between said magnet-cores and said arms. These arms 13, 13 13respectively carry contacts 15, 15 15", which are respectively insulatedfrom said arms and electrically connected as hereinafter described.

16, 16, 16 represent coils of comparatively low resistance respectivelywound on Said last mentioned magnet coils are here shown connected inseries and the direction of the current flowing in these coils 16, 16,16 is such as to oppose the magnetic flux set up by coils 11, 11, 11 18and 13 are other coils of comparatively low resistance woundrespectively on the magnet-cores 17 17 19, 19, 19 are adjustment screwspreferably made of some nonmagnetic material and adapted to adjust theair gaps between magnet-cores 17, 17, 17" and the movable arms 13, 13 13Wire 20 connects contact 15 with the armature-circuit, intermediate coil18*, and resistance 10. lVire 20 connectscontact 15 with thearmature-circuit, intermediate-coil 18 and resistance 10". lVire 2Oconnects contact 15 with the armature-circuit, intermediate resistance10, and line 8.

I- preferably connect contact 15", inter mediate coils 16, 16, 16", andline 8 so that when arms 13, 13, 13 have performed their functions and10, 10, 10 have been cut out, the coils 16, 16, 16 will also beshort-circuited. Following out the armature-circuit from line 1 itpasses by means of switch 3 and wire 7 to the armature 4r, thencethrough the armature of the motor and by means of wire 30 to resistance10, thence through resistance 10, wire 21, coil 18 wire 22, wire 23,resistance 10*, wire 24, coil 18*, wire 25, wire 26, resistance 10, wire27, coil 16, wire 28, coil 16, wire 29, coil 16*, wire 31, wire 8 andswitch 3 to line wire 2.

The operation of my invention is as follows: Assuming the main line tobeclosed by switch 3, the current flows from wire 1 through switch 3, wire5, magnetc'oils 11, 11, 11 and returns by wire 6 and switch 3 to thenegative side of the line represented by wire 2. The flow of suchcurrent being of practically constant value causes the coils 11, 11 11to exert a practically constant pull on arms 13, 13, 13 because'of themagnetization these coils set up and maintain in cores 17, 17, 17 solong as switch 3 remains closed. The arms 13, 13",.13 are preferably ofsuch material as to be attracted by the magnets 17, 17, 17 when saldmagnets are energized by coils 11, 11, 11 but the mehanical constructionand adjustment of said arms is such as to have sufficient space betweensaid arms and said magnets to prevent the attraction of said arms untilthe operation of the armature of the motor 1, which is assumed to havecommenced to rotate because of the rush of current, taking place whenswitch 3 is closed, has developed sufficient counter electro motiveforce to weaken the current flowing in the armaturecircuit and coils18*, 18", 16, 16, 16 to such an extent that the magnetic flux setup bycoil 16 in opposition to that set up by coil 11 is no longer suflicientto prevent the attraction of arm 13 by core 17. Arm 13 now moves overand 15 contacts with 12 shortcircuiting. resistance 10 and with it coil18 and the armature-current now passes from the armature through wire30, wire 33, contact 12, contact 15, wire 20, wire 23 to resistance 10,because the resistance of this path is much less than that throughresistance 10 and coil 18 It will be observed that when the current incoil 16 has become weakened to such an extent as to allow core 17 toattract arm 13 the current in coils 16 and .16 has also been weakened tothe same extent, but the arms 13 and 13 do not move over because thecoils 18 and 18 are at this stage working in conjunction with coils 16and 16 to reduce the magnetization set up by coils 11 and 11". Theresistance 10 and coil 18 having been short-circuited by contacts 15 and12 the current in the armaturecircuit immediately increases to such anextent that this armature current which is now also passing through coil16 and magnetizing core 17 in opposition to coil 11 is sufficient toprevent the movement of arm 13 until such time as the counter-electro-mdtire-force, generated by the armature, causes the current in coil 16again to reduce to a point where the magnetization set up by coil 11will attract arm 13 and cause 15 and 12 to c'ome in contact, thusshort-circuiting resistance 10 and coil 18". The currentagainimmediately rises in the armaturecircu-it so that this increasedcurrent work ing through coil 16 in opposition to coil l1 prevents themovement of arm 13 until the current again drops and weakens coil 16enough to allow core 17 to act on arm 13. 'Arm 13 now moves over and 15contacts with 12 short-circuiting resistance 16 and otherwise beincident to the-constant flow of current through coils 16, 16*, 16 Whenthe mea re arms 13, 13 13 have been attracted by magnets 17, 17 17 so asto cause contacts 12 and 15, 12 and 15, 12 and 15 respectively to comeinto contact, the current through the armature-circuit passes from line1, switch 3, line 7, motor 4, wires 30, 33, 33, and 8 back to switch 3and thence to line 2.

In my apparatus as I have here illustrated it, the operation of switch 3to disconnect main lines 1 and 2 from the armature and shunt-circuitsand thus deenergize magnets 17, 17 and 17, will cause the arms 13,13, 13to operate by gravity and resume the positions indicated in the drawing.I have not considered it necessary to illustrate or describe anymeansfor facilitating this return movement of said arms, it beingobvious that if it be necessary or desirable to do so, any

'- well-known means may be adopted to accomplish that result. In actualoperation it has been found suflicient to allow such arms to drop bygravity.

What I claim and desire to secure by Letters Patent is 1. Thecombination with a motor, of resistance in the armature circuit, a shuntcircuit, a series of magnets each having a coil connected in the shuntcircuit and a coil connected in thearmature circuit, an additional coilin the armature circuit on each except the first of said magnets, allcoils in the armature circuit being similarly wound, but differentiallywound from the coils in the shunt circuit, a series of contacts, oneoperated by each of said magnets, to cut out a section of resistanceinthe armature circuit and simultaneously therewith a magnet coil in thearmature circuit on the magnet next succeeding the magnet which hascaused a contact to operate, and means to short circuit all said coilsin. the armature circuit when the last magnet operates.

2: The combination with a motor, of resistance in the armature circuit,a shunt circuit, a series of magnets each having a coil connected .inthe shunt circuit and a coil connected in the armature circuit, anadditional coil on all but one of said magnets and connected in thearmature circuit, all

coils in said armature circuit being similarly wound but differentiallywound from the coils in the shunt circuit and contacts operated by saidmagnets, so connected in the armature circuit as to cut out a section ofresistance and a coil in the armature c rcuit on the magnet nextsucceeding the magnet which has caused a contact to operate when thecurrent of the armature'circuit reaches a predetermined value and to cutin such resistance and such coils in the armature circuit if the currentof the armature circuit afterward goes higher than another predeterminedvalue. r

3, The combination of an electric motor,

resistance in the armature circuit, a plu 'rality of magnets energizedfrom a shunt circuit, a coil on one of said magnets connected in thearmature circuit so as to oppose the operation of said magnet, aplurality of coils on another magnet connected in the armature circuitsoas to oppose the net until the current in the armature circuitdrops toa predetermined value, a plurality of coils on another magnet andconnected in the armature circuit so as to oppose and prevent the'operation of said last-mentioned magnet until said first-mentionedmagnet has operated and contacts controlled by said magnets and soconnected in the armature circuit as to cut out a section of resistanceand a coil in the armature circuit on the magnet having the plurality ofcoils when the current in the armature circuit has dropped to suchpredetermined value.

5. In' combination, an electric motor, resistance in the armaturecircuit, a plurality of contacts connected with, and arranged to cutresistance outof the .armature circuit, step by step, when actuated bysaid magnets, a coil on each of said magnets, connected in the armaturecircuit to oppose the operation of said magnets, an additional coil onall but one of said magnets and connected in the armature circuit tofurther oppose the operation of any magnet having such additional coil,until the next preceding magnet has operated.

6. In combination, a motor, resistance in the armature circuit, a magnetenergized by a shunt circuit, a movable member controlled by. saidmagnet and connected with the armature circuit so as to short-circuit asection of said resistance and a coil in the armature circuit on thenext succeeding magnet when said movable member is actuated by saidfirst-mentioned magnet, a coil on said first-mentioned magnet connectedin the armature circuit to oppose the operation of said first-mentionedmagnet until the current in the armature circuit has dropped to apredetermined value, another magnet energized by said shunt circuit, amovable member controlled by said last-mentioned magnet. and connected,with the armature circuit so 'as to short-circuit another section ofsaid resistance when actuatedbv said last-mentioned magnet and aplurality of resistance in the armature circuit, a shunt circuit, aplurality of magnets, a coil on each of said magnets connected in theshunt circuit, a coil on each of said magnets connected in the armaturecircuit, an additional coil on all but one of said magnets andconnected-in the armature circuit, all said coils in said armaturecircuit being similarly wound, but difierentially wound from the coilsin the shunt circuit, means controlled by said magnets to short-circuita section of armature resistance together with a coil 'in the armaturecircuit on the magnet next succeeding the magnet in operation, and meansto short circuit all the coils in the armature circuit on said magnetswhen the last of said magnets operates.

8. Thecombination of an electric motor, resistance in the armaturecircuit, a lurality of magnets constantly energized from a shuntcircuit, a coil on each of said magnets connected in the armaturecircuit, an additional coil on all but one of said magnets alsoconnected in the armature circuit, and a contact for and operated byeach magnet, said coils in the armature circuit being difierentiallywound from the coils in the shunt circuit and all said coils and saidcontacts be-v ing so arranged and connected that said magnets will becaused to operate successively, as the current of the armature circuitdrops, to cut out a section of resistance and one coil in'the armaturecircuit on the magnet next succeeding the magnet which has operated.

9. The combination of an electric motor,

resistance in the armature circuit, a plurality of magnets constantlyenergized from a shunt circuit, a coil on one of said magnets andconnected in the armature circuit so as to oppose and prevent theoperation of said magnet'until the current of the armature circuit dropsto a predetermined value, a plurality of coils on the other ofsaidmagnets, all said coils on said last-mentioned magnet beingconnected in the armature circuit so as to oppose and prevent theoperation of said last-mentioned magnet until said first-mentionedmagnet has operated, and contacts controlled by said magnets and soconnected in the armature circuit as to cut out a section of resistanceand a coil in the armature circuit on the magnet-having the plurality ofcoils when the current in the armature circuit has dropped to suchpredetermined value but to leave in operation the other coil on saidlast mentioned magnetand the coil on said first-mentioned magnet.

'10. The combination of an electric motor, resistance in the armaturecircuit, a plurality of magnets energized from a shunt circuit, a coilon each of said magnets connected in the armature circuit, an additionalcoil on all but one of Said magnets also connected in the armaturecircuit, contacts operated, one by each of said magnets, and soconnected in the armature circuit that the operation of a magnet willcut out a section of resistance and a coil on the next succeeding magnetwhen the current of the armature circuit drops to a predetermined valueand all said coils in the armature circuit will be shortcircuited whenthe last magnet operates.

In witness whereof, I have hereunto set my hand in the presence of twosubscribing witnesses, this the thirteenth day of April, 1910.

WILLIAM S. SMITH. Witnesses:

V. GLADYS S'IQ'OWE, FRANK B. FLINT.

